Diaphragm pump

ABSTRACT

A diaphragm pump, particularly for use as a fuel pump in an internal combustion engine, comprises upper and lower housing parts separated by a diaphragm which is clamped between them. The upper housing part comprises an intermediate housing and a top cover fixed on top of it. The intermediate housing has a cross wall which extends across the interior of the upper housing part and which, together with a valve plate within the intermediate housing, divides the upper housing part into three separate chambers, a suction chamber to which the pump inlet is connected, a working chamber, and a pressure chamber to which the pump outlet is connected. The working chamber is situated between the valve plate and the diaphragm. A sunken port is press formed or drawn integrally from the cross wall in an eccentric position, the lower lip of this sunken port being sealed to the valve plate around a corresponding aperture in the valve plate. In this way a passageway is formed communicating the chamber above the cross wall, preferably the suction chamber, with the working cyamber. The seal at the lower lip of the sunken port is formed either by a sealing ring or by the lip being directly fixed to the valve plate.

[111 3,811,803 May 21, 1974 [5 DIAPHRAGM PUMP [75] Inventor: GuntherFrohberg, Neuss/Rhine,

Germany [73] Assignee: A. Pierburg Auto-und 'Luftfahrtgeraete KG,Neuss/Rhein, Germany 221 Filed: Jan.6, 1972 21 Appl. Neg 215,767

Related US. Application Data [62] Division of Ser. No. 864,337, Oct. 7,1969,

abandoned.

[30] Foreign Application Priority Data" 3,364,870 1/1968 Quatredenierset al. 417/571 Primary E xaminer William L. Freeh AssistantExaminer-Leonard Smith 57 ABSTRACT A diaphragm pump, particularly foruse as a fuel pump in an internal combustion engine, comprises upper andlower housing parts separated by a diaphragm which is clamped betweenthem. The upper housing part comprises an intermediate housing and a topcover fixed on top of it. The intermediate housing has a cross wallwhich extends across the interior of the upper housing part and which,together with a valve plate within the intermediate housing, divides theupper housing part into three separate chambers, a suction chamber towhich the pump inlet is connected, a working chamber, and a pressurechamber to which the pump outlet is connected. The working chamber issituated between the valve plate and the diaphragm. A sunken port ispress formed or drawn integrally from the cross wall in an eccentricposition,

the lower lip of this sunken port being sealed to the valve plate arounda corresponding aperture in the valve plate; In this way a passageway isformed com- I municating the chamber above the cross wall, preferablythe suction chamber, with the working cyamber. The seal at the lower lipof the sunken port is formed either by a sealing ring or by the lipbeing directly fixed to the valve plate.

. 3 Claims, 7 Drawing Figures l DIAPHRAGM 'PUMP filed Oct. 7, l9'69, nowabandoned,

This invention relates to diaphragm pumps, such as fuel pumps forinternal combustion engines, of the kind comprising upper and lowerparts separated by a diaphragm, the upper part comprising anintermediate housing upon which is attached a top cover, and theintermediate housing having a cross wall which, together with a valveplate, divides the upper part of the pump into a suction chamber, aworking chamber and a pressure chamber, the working chamber beinglocated be tween the valveplate and the diaphragm.

Diaphragm pumps of this kind for use as fuel pumps are known in whichthe valve plate, which contains an inlet valve and an outlet-valve,separates both the suction chamber situated above the inlet valve, andthe pressure chamber situated above the outlet valve, from the workingchamber situated above the diaphragm. The suction chamber isseparatedfrom the pressure chamber by means of a special part which rests incontact, on the one hand, with the valve plate and on the other handwith the lower surface of the cross wall of the intermediate housing.However, this type of pump is fairly costly to construct, in the firstplace due to the fact that it consists of four main parts, i.e. the topcover, the intermediate housing, the valve plate and the separatingpart, and in the second place because a double seal is required at thetwo ends of the sealing part where it joins the valve plate and thecross wall. A further disadvantage, of this known'fuel pump is that thetop cover. which is mounted concentrically on the intermediate housingby means of an'annular flange and which contains the suction chamber, isnevertheless attached to the intermediate housing by a screw insertedeccentrically in the top cover, with the result that the top cover,which contains the fuel inlet connection to the pump. can be mounted onthe intermediate housing, which contains the fuel outlet connection,only in one particular position. Any change in the relative anhousingcontains a sunken port which is press formed or drawn integrally fromthe cross wall in an eccentric position, the lower lip of the sunkenport resting tightly in contact with or closely adjacent the surface ofthe valve plate surrounding a corresponding aperture in the valve plate,and a seal being formed between the lower lip and the valve plate sothat a passageway is formed between the chamber above the cross wall andthe working chamber below the valve'plate.

ln this way a pump isobtained which consists of only three main parts,the top'cover, the intermediate housing and the valve plate, and is thusextremely simple to manufacture and assemble.

. Preferably the fluid inlet and outlet connections for the pump arefixed to the top cover and the intermediate housing respectively, andthe top cover is mounted concentrically on the intermediate housing bymeans of a centrally placed screw. Therefore, during assembly of thepump it is quite easy to adjust the angle between the fluid inletconnection and the fluid outlet connection, and also the angle betweenthe fluid outlet connection and the body of the pump. The angle betweenthe two fluid connections is adjusted, during assembly of the pump, byrotating the top cover relative to the intermediate housing and thentightening the screw. The angle between the fluid outlet connection andthe body of the pump is adjusted by rotating the intermediate housingrelative to the body of the pump. Alternatively, a different angle canbe obtained between the fluid outlet connection and the body of thepump, by suitably positioning the opening in the intermediate housingfor receiving the fluid outlet connection, i.e., by suitably positioningthe fluid outlet connection, relative to the position of the port in thecross wall of the intermediate housing between the suction chamber andthe working chamber.

The construction of thepump in accordance with the invention greatlyfavours application of the buildingblock principle, so that furtherstructural units can be added to the pump according to requirements,thus greatly increasing the field of application of the pump. Thisadvantage is obtained irrespective of whether the port in thecross wallof the intermediate housing is attached to the'valve plate'directly,such as by adhesive bonding, braising or welding, or is attached withthe interposition of a resilient sealing ring. Direct attachment bybonding is preferred, for the sake of lower manufacturing cost andbecause it provides a more rigid structure and this method still allowsfurther structural units to be added to the pump. For example the crosswall of the intermediate housing between the pressure chamber and thesuction chamber can contain a pressure relief valve, for releasing theexcess pressure which can build up in the pressure chamber when theengine is running hot, by evaporation of fuel.

As a further possibility the cross wall of the intermediatehousing,between the pressure chamber and the suction chamber, may contain anaperture sealed off by a flexible membrane which is preferably springloaded by a compression spring on the suction chamber side of the outputof the pump.

'As a still further possibility, for releasing excess pressure in thepressure chamber, there may be interposed between the wall of theintermediate housing and the valve plate an auxiliary valve plate toform a pressure chamber and a delivery chamber, the auxiliary valveplate containing a pressure reducing valve. This valve is preferablycontrolled by a control membrane which is acted on by a spring on oneside and by the pressure in the pressure chamber on the other side, thecontrol membrane being arranged in a housing which is mounted on thecross wall and projects into the suction chamber.

As a still further possibility, for certain particular applications, thepump can contain a device for isolating the suction chamber from thepressure or delivery chamber when the pump is not in use. For thispurpose a pair of auxiliary plates which enclose a delivery chamber maybe arranged in the pressure chamber between the cross wall of theintermediate housing and the valve plate, the pressure chambercommunicating with one side of a spring loaded control membrane which,in use, opens a valve under the action of the pressure in the pressurechamber to connect the presthe pump stops, closes this valve.

Several examples of diaphragm pumps in accordance with the presentinvention are now described with reference to the accompanying drawings,in which:

FIG. 1 is a longitudinal section through a diaphragm fuel pump suitablefor use in an internal combustion engine;

FIG. 2 is a longitudinal section through the upper part of a modifiedform of the fuel pump shown in FIG.

FIG. 3 is a longitudinal section through part of the fuel pump shown inFIG. 1, but illustrating a modification to the pump;

FIG. 4 is similar to FIG. 3, but shows a different modification;

FIG. 5 is a longitudinal section through the upper part of anotherexample of a diaphragm fuel pump in accordance with the invention;

FIG. 6 is a similar view to that of FIG. 5, but shows a further example;and.

FIG. 7 is a longitudinal section through the upper part of the pumpshown in FIG. 1, but showing a slight modification.

The diaphragm fuel pump illustrated in FIG. 1 is shown in an uprightposition and has a diaphragm I mounted in a known way between the upperand lower parts of the pump body. The diaphragm 1 is driven inoscillation, when the pump is in operation, through a reciprocatingdrive rod which slides in a bush in the lower part of the pump body.Above the diaphragm I within the upper part of the pump there are threechambers, a suction chamber 2, a working chamber 3 and a pressurechamber 4. The working chamber 3 is situated immediately above thediaphragm 1 and is enclosed by the diaphragm and a valve plate 5 whichcontains a valve port 50 for an inlet valve 26, and valve port 512 foran outlet valve 26. The port 5a communicates with the suction chamber 2and the port 5b with the pressure chamber 4. The upper part of the pumpbody is formed by two superposed inverted cupshaped members, i.e., anintermediate housing 6 and a top cover 7. The outer rim of theintermediate housing 6 is rolled over the outer rim of the lower part ofthe pump body, as shown at 6a in FIG. 1, the outer rims of the valveplate 5 and the diaphragm I being secured to the rim ofthe lower part ofthe pump body by clamping between the rolled rim 6a of the intermediatehousing 6 and the rim of the lower part of the pump body, so as to forma combined sealed joint between these four parts. The top cover 7 ismounted on the intermediate housing 6 with a flange 7a around its rimengaging over the heel of the intermediate housing 6, and is fixed inposition by means of a central screw 33 which engages in an internallyscrew threaded hole in the middle of the cross wall 8 of theintermediate housing 6. The cross wall 8 contains, eccentricallylocated, a sunken port or aperture 9 formed by a press operation andcorresponding to the port 50 in the valve plate 5. The lower rim 9a ofthe port 9 lies adjacent the upper surface of the rim of the port 5a anda seal is formed between them by means of an elastic sealing ring 10.

With this arrangement the three chambers of the pump, i.e., the suctionchamber 2, the working chamber 3 and the pressure chamber 4, arehydraulically separated from each other by the two internal walls in theupper part of the pump body. These are the cross wall 8 of theintermediate housing 6, and the valve plate 5. Thus, the suction chamber2 is contained by the top cover 7, the working chamber 3 is above thediaphragm l and below the valve plate 5, and the pres sure chamber 4 isto one side between the valve plate 5 and the cross wall 8. On the rightof FIG. 1 the valve plate 5 contains the outlet port 5b. A valve housing26a, whose upper surface rests against the lower surface of the crosswall 8, contains the outlet valve 26' which is spring loaded towards theclosed position by a compression spring 26b. The suction chamber 2contains a filtering screen 35, and there is a sealing ring 34interposed between the flange 7a and the heel of the intermediatehousing 6. The rim of the screen 35 is squeezed between the sealing ring34 and the flange 7a.

The top cover 7 has a side opening36 into which is welded or braised orotherwise firmly secured a fuel inlet connection 28. Similarly, theintermediate housing 6 has a side opening 37 into which is securelybonded an outlet connection 27. This construction has the advantage thatthe angular positions of the inlet and outlet connections, relative toeach other, can easily be adjusted, either during assembly of the pump,or by simply loosening the central screw 33, rotating the top cover 7relative to the intermediate housing 6, and finally tightening the screwagain.

The example shown in FIG. 2 differs from FIG. 1 in that the sunken inletport 9'has a different lip 9a, and is sealed to the valve plate 5 in adifferent manner. F urthermore the fuel inlet and outlet connections tothe pump are differently attached to the upper part of the pump. In FIG.2 the lip 9a of the inlet port 9, which is an essentially cylindricalextension formed by a drawing operation, rests directly on the uppersurface of the valve plate 5 surrounding the port 5a without anyintermediate seal, the two surfaces being bonded together by means of anadhesive, or by being braised or welded together. With regard to theinlet and outlet fuel connections, in FIG. 2 each connection 29, 30 hasan external flange 31, 32, which is braised or welded to the housingpart 6, 7 around the ports 36, 37 respectively. This arrangement stillallows the housing parts 6 and 7 to be easily adjusted in angularposition relate to each other merely by first loosening the centralscrew 33.

The way in which the diaphragm fuelpump shown in FIGS. 1 and 2 functionsis as follows:

On the down stroke of the diaphragm I as it is oscillated by the drivingshaft, fuel is sucked into the chamber 2 through the inlet connection28, 30. The fuel in the suction chamber 2 flows through the filterscreen 35 and through the inlet valve 26 into the working chamber 3,situated above the diaphragm 1. During the driving or up stroke of thepump the diaphragm 1, moving upwards, closes the inlet valve 26 andopens the outlet valve 26'. The fuel is expelled from the workingchamber 3 into the pressure chamber 4 and from there is deliveredthrough the outlet connection 27, 29. The outlet connection is connectedby a pipe to the carburettor or fuel injection pump of the Otto cycle orDiesel cycle engine (not shown).

In the example shown in FIG. 3 the part of the cross wall 8 of theintermediate housing 6 which bounds the pressure chamber 4 contains apressure relief valve 11, consisting of a ball 11b loaded by acompression spring 11a and seating on an orifice 12 forming a passagethrough the cross wall 8 and through the top of the housing 26a of theoutlet valve 26'. The pressure relief valve 11 prevents an excessivepressure from building up in the pressure chamber 4 when fuel evaporatesfrom a hot engine. As soon as the pressure increases to beyond thepermitted value it lifts the ball llb allowing fuel to escape from thepressure chamber 4 through the orifice 12 into the suction chamber 2under the top cover 7.

The pump shown in FIG. 4 provides for absorption of the pressure peaksin the pressure chamber 4, thus increasing the output of the pump. Anelastic membrane 13 is stretched across an opening in the cross wall 8between the pressure chamber 4 and the suction chamber 2, and is springloaded by a compression spring 14 situated on the suction chamber sideof the membrane 13 and contained in a support housing 14a. The elasticmembrane 13 absorbs pressure peaks in the pressure chamber 4 by flexingelastically upwards.

In certain cases it is desirable-to absorb an excessive pressure buildup within the pump before it reaches the outlet connection of the pump.An arrangement for doing this is shown in FIG. 5. An auxiliary valveplate 15 containing a pressure reducing valve 16, is interposed betweenthe cross wall 8 of the intermediate housing 6 and the valve plate 5 toform a pressure chamber-4 and a delivery-chamber 18. The pressurereducing valve 16 consists of a housing 16a containing a spring loadedball [60, loaded by a compression spring 16b. The ball 16c rests againstthe end of a plunger 17a attached to a control diaphragm 17 mounted in ahousing 17b. The upper surface of the control diaphragm 17 is springloaded by a compression spring 17c contained in the upper part of thehousing 1711, which has an orifice 19 opening into the suction chamber2. The pressure in the delivery chamber 18, acting on the lower surfaceof the control diaphragm 17 controls the flow of fuel delivered by thepump. The ball valve therefore acts as a pressure control valve,controlling the pressure in the delivery passage 18. It should beobserved that in the example of FIG. 5 the central screw 33, which holdsthe top cover 7 down on its seat, screws into a stirrup 38 resting onthe intermediate housing 6.

In some cases it is necessary to block the passage be tween the suctionchamber and the pressure chamber chamber 4 there is an aperture 23passing through the two auxiliary plates 20, 21 which are in contactwith each other around the periphery of the aperture 23 to form a sealagainst each other. The aperture 23 con-- nects the pressure chamber 4to the lower surface of a control diaphragm 24, whose upper surface isloaded by a compression spring 39 contained in a housing 40. The housing40 contains an orifice 41 which connects the suction chamber 2 to thespace above the diaphragm 24. This diaphragm controls a valve 25consisting of a valve seat 25a mounted in the separating plate 21, avalve disc 25b'and an inner valve housing 250. When the pump is at astandstill the valve 25 is closed, as long as the pressure is notexcessive in the pressure 6 chamber 4. However, a pressure buildup m thepressure chamber 4 acts on the control diaphragm 24, lifting the valvedisc 25b and opening the valve 25 so that a connection between thedelivery chamber 22 and the pressure chamber 4 is established, allowingfuel to flow out into the carburettor. In the pump shown in FIGS. 6 and7 the ports 5a and 5b are provided with valve members 50' and 5brespectively which are made of conventional elastomer material, therebycausing the respective valves to act unidirectionally.

The pump shown in FIG. 7 is substantially the same as the pump shown inFIG. 1, but with the difference that in FIG. 7 the inlet valve 26 is notlocated in the valve plate 5, but rather in the interior of the sunkenport 9, whichis a part of the intermediate housing 6. This pump,however, still functions in the same way as the pumps shown in FIGS.land 2.

The main advantages of the diaphragm pump according to the invention arethat, in the first place, the pump contains few parts and is easy tomanufacture and assemble. A further great advantage is that theconstruction of the pump greatly favours application of thebuilding-block principle, so that furtherparts can easily be added tothe pump, at verylittle extra cost.

I claim:

-1. A diaphragm pump having upper and lower housing parts,

means fixing said upper and lower housing parts to each, other,

a diaphragm clamped between said upper and lower housing parts, I

said upper housing part comprising an intermediate housing, a top coverand a valve plate,

means fixing said top cover on said intermediate housing,

a pair of unidirectional flow valves directly mounted on said valveplate,

a cross wall forming part of said intermediate housing, having integraldepending wall means projecting from said cross-wall toward said valveplate and deformed to define an eccentrically located annular recesshaving a central opening through said cross wall,

aperture defining means in said valve plate corresponding to saidcentral opening,

the bottom of said annular recess lying closely to said aperturedefining means,

an auxiliary valve plate means mounting said auxiliary valve platebetween said cross wall and said valve plate to form a pressure chamberand a delivery chamber,

a pressure reducing valve, and

means mounting said pressure reducing valve in said auxiliary valveplate,

said suction chamber is located within said top cover above said crosswall, and said pressure chamber is located between said auxiliary valveplate and said valve plate, whereby said upper housing part is dividedby said valve plate, said auxiliary valve plate and said cross wall intofour chambers consisting of a working chamber above said diaphragm andbelow said valve plate, a suction chamber and a pressure chamber, and adelivery: chamber, with said annular recess forming a passage waybetween the chamber above said cross wall and said working chamber. v

, 2. A diaphragm pump as claimed in claim 1, wherein said pressurereducing valve is controlled by means comprising a housing mounted onsaid cross wall and projecting into said suction chamber, a controlmembrane stretched across the interior of said housing, spring meanswithin said housing and acting on one side of said control membrane, andmeans by which the pressure in said delivery chamber communicates with3. A diaphragm pump as claimed in claim 2, wherein said housing for saidcontrol membrane contains means defining a throttling orifice whichconnects said suction chamber to the side of the membrane on which saidsaid housing to act on the opposite side of said control spring meansacts.

membrane from said spring means.

UNITED I STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pete'nt No.3,811,803 Dated May 21, 1974 Gunther FROHBERG lnventor(s) It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

On page 1 correct the spelling of the name of the v. assignee bycancelling the present spelling and substituting therefore thefollowing:

-A. Pierburg Auto- I und Luftfahrt-Geraetebafl KG.

Neuss/Rhein, Germany Signed and sealed this 7th day of January 1975.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL DANN Attesting .O ff icer Commissionerof Patents FORM Po-wso (10-69) I 1 v USCOMM-DC scam-P69 w u.s.GOVEIRNM'ENTYFRINTING OFFICE I969 o-sss-au

1. A diaphragm pump having upper and lower housing parts, means fixingsaid upper and lower housing parts to each other, a diaphragm clampedbetween said upper and lower housing parts, said upper housing partcomprising an intermediate housing, a top cover and a valve plate, meansfixing said top cover on said intermediate housing, a pair ofunidirectional flow valves directly mounted on said valve plate, a crosswall forming part of said intermediate housing, having integraldepending wall means projecting from said cross-wall toward said valveplate and deformed to define an eccentrically located annular recesshaving a central opening through said cross wall, aperture definingmeans in said valve plate corresponding to said central opening, thebottom of said annular recess lying closely to said aperture definingmeans, an auxiliary valve plate means mounting said auxiliary valveplate between said cross wall and said valve plate to form a pressurechamber and a delivery chamber, a pressure reducing valve, and meansmounting said pressure reducing valve in said auxiliary valve plate,said suction chamber is located within said top cover above said crosswall, and said pressure chamber is located between said auxiliary valveplate and said valve plate, whereby said upper housing part is dividedby said valve plate, said auxiliary valve plate and said cross wall intofour chambers consisting of a working chamber above said diaphragm andbelow said valve plate, a suction chamber and a pressure chamber, and adelivery chamber, with said annular recess forming a passage way betweenthe chamber above said cross wall and said working chamber.
 2. Adiaphragm pump as claimed in claim 1, wherein said pressure reducingvalve is controlled by means comprising a housing mounted on said crosswall and projecting into said suction chamber, a control membranestretched across the interior of said housing, spring means within saidhousing and acting on one side of said control membrane, and means bywhich the pressure in said delivery chamber communicates with saidhousing to act on the opposite side of said control membrane from saidspring means.
 3. A diaphragm pump as claimed in claim 2, wherein saidhousing for said control membrane contains means defining a throttlingorifice which connects said suction chamber to the side of the membraneon which said spring means acts.